Buggy code:
public class PFlow { private final Manipulator m ; public final Channel < QCAVector > answer = new org . jetlang . channels . MemoryChannel < QCAVector > ( ) ; public final Channel < PFlow > question = new org . jetlang . channels . MemoryChannel < PFlow > ( ) ; public final Channel < Throwable > stop = new org . jetlang . channels . MemoryChannel < Throwable > ( ) ; protected final PFlow parent ; private Relationship op = null ; private Node opNode = null ; private Vector < QCAVector > path = new Vector < QCAVector > ( ) ; public PFlow ( Manipulator m ) { } public PFlow ( Manipulator m , Relationship op ) { } public PFlow ( PFlow parent ) { } @ Deprecated public PFlow ( PFlow parent , Relationship op ) throws AnimoException { } public PFlow ( PFlow parent , Node opNode ) { } public PFlow ( PFlow parent , QCAVector vector ) { } protected void cyclingDetection ( ) throws AnimoException { } private void cyclingDetection ( Relationship op ) throws AnimoException { } public PFlow getParent ( ) { } public Relationship getOP ( ) { } public Relationship getStartOP ( ) { } public Node getStartNode ( ) { } public Node getOPNode ( ) { } protected void setOPNode ( Node opNode ) { } public void sendAnswer ( QCAVector r ) { } public void sendAnswer ( Relationship answer ) { } public void sendAnswer ( Relationship answer , RelationshipType rType , byte [ ] hash ) { } public void sendAnswer ( QCAVector answerVector , RelationshipType rType ) { if ( ( parent ) == null ) { System . out . println ( "WORNG<seq2seq4repair_space>-<seq2seq4repair_space>no<seq2seq4repair_space>parent" ) ; throw new IllegalArgumentException ( "NULL<seq2seq4repair_space>parent<seq2seq4repair_space>@pflow" ) ; } else { Relationship answer = Utils . createResult ( this , answerVector . getContext ( ) , op . getEndNode ( ) , answerVector . getAnswer ( ) , rType ) ; <START_BUG> parent . answer . publish ( new QCAVector ( op , answer , answerVector . getContext ( ) ) ) ; <END_BUG> } } public void sendAnswer ( Relationship answer , QCAVector context ) { } public void sendAnswer ( Relationship question , QCAVector context , Relationship answer ) { } public void sendException ( Throwable t ) { } public void done ( ) { } protected CountDownLatch waitBeforeClosePipe = null ; public void waitBeforeClosePipe ( int count ) { } public void countDown ( ) { } public void countDown ( PipedOutput < ? > out ) { } public void await ( ) { } public Manipulator getManipulator ( ) { } public List < QCAVector > getPFlowPath ( ) { } public Path getFlowPath ( ) { } public Iterable < Relationship > stack ( ) { } private class PFlowStack implements Iterable < Relationship > , Iterator < Relationship > { private Iterator < Relationship > it = getFlowPath ( ) . relationships ( ) . iterator ( ) ; private Relationship pos = step ( ) ; private Relationship step ( ) { } @ Override public boolean hasNext ( ) { } @ Override public Relationship next ( ) { } @ Override public void remove ( ) { } @ Override public Iterator < Relationship > iterator ( ) { } } public Iterable < Relationship > getStackContext ( Relationship r , boolean goDown ) { } public QCAVector addContextPoint ( QCAVector vector ) { } public QCAVector addContextPoint ( Relationship r ) { } public void popContextPoint ( QCAVector vector ) { } public byte [ ] getPathHash ( ) { } public byte [ ] getOpHash ( ) { } public Relationship getLastContext ( ) { } private TraversalDescription get_td_flow ( ) { } public boolean isInStack ( Relationship r ) { } public void debug ( ) { } private void ops ( StringBuilder sb ) { } public QCAVector getVector ( ) { } }

Fix:
parent . answer . publish ( new QCAVector ( op , answer , answerVector . getContext ( ) , answerVector . getPrecedingSibling ( ) ) ) ;